On Dec 10, 2007 2:31 PM, <[EMAIL PROTECTED]> wrote:
snip
> But I did stick an undef in at if (!$OutputFile) so
> if (undef $OutputFile)
>
> Then the warning moved on to line 66 where the code attempts to use
> OutputFile. Seems to indicate OutputFile was gettiong a varlue in the
> if clause.
snip
That does not do what you think it does. The undef function makes its
argument variable undefined. You are looking for the defined function
like this
if (not defined $OutputFile) {
or this
unless (defined $OutputFile) {
depending on your tastes. Also, there are better ways to write that code:
my $OutputFile = shift || "/home/reader/projects/perl/work/myfile";
die "<$OutputFile> cannot be found .. exiting\n" unless -f $OutputFile;
The shift function defaults to @ARGV when called in the body of
program (it defaults to @_ in subroutines) and the or operator returns
the first true item (if any), so the construct shift || "default" will
return the value from @ARGV if it is set (and non-zero) or the default
value. The die function prints its argument to STDERR (with the file
and line number if it does not end with \n) and exits the program with
a non-zero error code. The new // operator that will be available in
Perl 5.10 returns the first defined item (if any). This makes it a
much better choice for defaulting logic like this.
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